Truss-type adjustable joist



Feb. 26, 1963 R. 5. BLACK TRUSS-TYPE ADJUSTABLE JOIST Filed Oct. 5, 1959Robert .S. Black INVENTOR.

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United States Patent Ofiflce 3,078,370 TRUSS-TYFE ADJUSTABLE 301$!Robert S. Elack, R0. Box 6385, Corpus Christi, Tex. Filed Oct. 5, 1959,Ser. No. 844,495 4 Claims. (Cl. 189-37) This invention relates toimprovements in truss-type joists longitudinally adjustable to vary thelength thereof according to the desired span and for supporting formsfor concrete roofs, decks, roadways, and the like.

By way of premise, such joists, as commonly constructed, depend forlongitudinal adjustment for varying the length thereof on insertionstherein of sections, spacers, washers, eccentrics, spacer plates or thelike, and in view of which they are complicated, too costly and requiretoo much time and labor to adjust the length thereof.

Having the foregoing in mind, the principal object of this invention isto provide a truss-type joist of simple, practical constructionlongitudinally adjustable easily and quickly, and in small increments ofadjustment and which may be manufactured at a low cost of stockmaterial, all without sacrificing strength and safety in the joists.

These together with other objects and advantages which will becomesubsequently apparent reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing had to the accompanying drawing forming a part hereof, whereinlike numerals refer to like parts throughout, and in which:

FIGURE 1 is a fragmentary view in plan of the improved joist in apreferred embodiment thereof, partly broken away;

FIGURE 2 is a view in side elevation of the same;

FIGURE 3 is an enlarged view in end elevation of the same;

FIGURE 4 is an enlarged view in vertical transverse section taken on theline 4-4 of FIGURE 2, and partly broken away;

FIGURE 5 is an enlarged fragmentary view in vertical transverse sectiontaken on the line 55 of FIGURE 2; and

FIGURE 6 is an enlarged fragmentary view in perspective partly insection of the joist.

Referring to the drawing by numerals, according to this invention, atruss-type joist is provided comprising a pair of like, side-by-side,overlapping, longitudinal sections 1, 3 respectively, each formingone-half of the joist.

The sections 1, 3 being alike a description of one will suflice forboth.

Each section 1, 3 comprises upper and lower relatively long 5 and short7 angle irons or chord members having vertically aligned inner ends, asat 9, 11 and vertical side flanges 13, 15 (FIG. 6). The inner ends 9, 11of the upper and lower chord members 5 and 7 of each section 1, 3 areconnected together by a rectangular steel plate 17 interposed betweenand butt welded, as at 19, to the edges of the vertical side flanges 13,15 coplanar With said flanges.

Transverse, angle truss bars 21 cross-connect the upper and lower anglebar chord members 5, 7 in parallel relation and are spaced apart alongsaid chord members and terminally welded, as at 2.3, to the verticalflanges 13, 15 to extend diagonally of said chord members 5, 7.

The overlapping portions of sections 1, 3 are bolted together with thevertical flanges 13 engaging flatly and the vertical flanges 15similarly engaging and by the following means. Upper and lower series ofbolts 25, 27 are provided for selective extension through longitudinallyspaced bolt holes 29, 31 in the vertical flanges 13, 15

3,fl'i8,97fl Patented Feb. 26, 1963 of the chord members 5, 7respectively. The bolt holes 29, 31 are spaced in the series 3 inchesapart in each flange 13, 15 so that the sections 1, 3 are adjustablelongitudinally relatively in increments of 3 inches for fine adjustmentto elongate or contract the joist according to the span required.

Preferably, there are three bolts, only, 25, 27 in each series and thesame are used at the plates 17, which is to say at the inner ends 9, 11of the chord members 5, 7 and said bolts are preferably three-quarterinch machine bolts.

A bearing seat is provided at the outer end of each section 1, 3comprising a pair of short angle plate members or cleats 41, welded asat 43, to the vertical flanges 13 of the upper chord member 5respectively, with each plate 41 welded, as at 45, to the outermost oneof the truss bars 21 which extends substantially to the outer end of theupper chord member 5.

As will now be seen, the described joist can be readily adjusted to thedesired length by two men and in adjusted position is well adapted towithstand stresses and strains. Furthermore, the joist can bemanufactured of standard stock parts of steel angle bars and stock sizesof flat steel plates, also stock bolts, all of which greatly reduce thecost of manufacture of the joist.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact constructure and operation shown anddescribed, and accordingly, all suitable modiflcatons and equivalentsmay be resorted to, falling within the scope of the invention asclaimed.

What is claimed as new is as follows:

1. For use as a section of a sectional adjustable trusstype bridgejoist, a prefabricated section comprising, in combination, a linearlystraight upper angle iron, a complemental linearly straight lower angleiron parallel to and spaced below the upper angle iron, said angle ironsbeing of duplicate cross-section and each including a vertical flangeand a horizontal flange, the vertical flanges being in a common plane,the corresponding inner ends of the upper and lower angle ironsterminating together, a flat-faced plate of a cross-sectional thicknesscorresponding to the thickness of the vertical flanges of the angleirons and interposed between and welded to the cooperating lengthwiseedges of said flanges, and a vertical longitudinal edge of said platebeing flush with the cooperating terminal ends of the vertical flanges,said vertical flanges having several bolt holes cooperating with thetransverse end portions of said plate, the end of the upper angle ironopposite to the locale of said plate extending beyond the correspondingend of the lower angle iron and being provided with L-shaped fixedlyattached cleats, said cleats providing bearing seats, and diagonalbraces connecting said upper and lower angle irons together.

2. The structure defined in claim 1 and wherein said braces are diagonaltruss bars of angular cross-section having end portions of flangesthereof overlapping surfaces of the vertical flanges of the upper andlower angle irons and being welded thereto and being spaced anddistributively arranged and interrelated to equalize stresses andstrains capable of coping with compression and tension requirements.

3. A longitudinally adjustable heavy duty truss-type highway bridgejoist comprising a pair of identical interchangeable side-bysidesections each section including duplicate upper and lower angle barchord members having vertical flanges, respectively, the verticalflanges of the chord members of said sections being engaged flatly andparallel, the chord members of each section having vertically alignedinner ends, a vertical plate inter posed between and connecting theinner lengthwise edges of the vertical flanges of said upper and lowerchord members, diagonal angle bars Welded to and positively connectingtheupper and lower chord members of eachsection, and rigid meanssecuring the flatwise flatly contacting yertical flanges together forlongitudinal adjustment of; said chord members relative to each otherand to enable one to adjust the sections for lengthening and shortingthe complete joist'at will,- said means comprising an upper series ofclosely associated and allied bolts extending through the inner ends ofthe engaged flanges of the upper chord members, and a correspondinglower series of closely allied bolts extending through the inner ends ofthe engaged flanges of the lower chord members, said flanges havingclose-together longitudinally spaced bolt holes therein for readyinsertion and removal of the bolts.

4. The adjustable joist construction according to claim 3 and whereinthe upper chord members only have outer projecting ends provided with anangle plate welded to the coacting vertical flange of the chord rnernberand related in size to the cross-section of the vertical flange tocooperate therewith and to provide a bearing seat, and said diagonalangle bans being spaced along each section and cross-connecting theupper and lower chord members together.

References (Iited in the file of this patent UNITED STATES PATENTS

1. FOR USE AS A SECTION OF A SECTIONAL ADJUSTABLE TRUSSTYPE BRIDGEJOIST, A PREFABRICATED SECTION COMPRISING, IN COMBINATION, A LINEARLYSTRAIGHT UPPER ANGLE IRON, A COMPLEMENTAL LINEARLY STRAIGHT LOWER ANGLEIRON PARALLEL TO AND SPACED BELOW THE UPPER ANGLE IRON, SAID ANGLE IRONSBEING OF DUPLICATE CROSS-SECTION AND EACH INCLUDING A VERTICAL FLANGEAND A HORIZONTAL FLANGE, THE VERTICAL FLANGES BEING IN A COMMON PLANE,THE CORRESPONDING INNER ENDS OF THE UPPER AND LOWER ANGLE IRONSTERMINATING TOGETHER, A FLAT-FACED PLATE OF A CROSS-SECTIONAL THICKNESSCORRESPONDING TO THE THICKNESS OF THE VERTICAL FLANGES OF THE ANGLEIRONS AND INTERPOSED BETWEEN AND WELDED TO THE COOPERATING LENGTHWISEEDGES OF SAID FLANGES, AND A VERTICAL LONGITUDINAL EDGE OF SAID PLATEBEING FLUSH WITH THE COOPERATING TERMINAL ENDS OF THE VERTICAL FLANGES,SAID VERTICAL FLANGES HAVING SEVERAL BOLT HOLES COOPERATING WITH THETRANSVERSE END PORTIONS OF SAID PLATE, THE END OF THE UPPER ANGLE IRONOPPOSITE TO THE LOCALE OF SAID PLATE EXTENDING BEYOND THE CORRESPONDINGEND OF THE LOWER ANGLE IRON AND BEING PROVIDED WITH L-SHAPED FIXEDLYATTACHED CLEATS, SAID CLEATS PROVIDING BEARING SEATS, AND DIAGONALBRACES CONNECTING SAID UPPER AND LOWER ANGLE IRONS TOGETHER.